Heat resistant resins such as polyimides, polybenzoxazoles, and the like have been widely used as an interlayer insulating layer and/or a planarization layer for a display device such as an organic light emitting diode (OLED), liquid crystal display (LCD), and the like. In particular, a heat resistant photosensitive polyimide and photosensitive polybenzoxazole have recently been used to form an interlayer insulating layer and the like in an OLED in order to secure reliability of the OLED.
The photosensitive polyimide and polybenzoxazole can have excellent physical characteristics such as heat resistance, mechanical strength and the like, excellent electrical characteristics such as a low dielectric constant, a high insulation property, and the like, good planarization characteristics on a coating surface, include small amounts of impurities that can deteriorate reliability of a device, and easily form a fine shape. In particular, positive-type photosensitive polyimides and polybenzoxazoles may be used in a pattern process and the like and can have pattern accuracy applicable to pattern an insulation layer and a planarization layer for an organic light emitting diode and thus, are very advantageous in terms of processability, economics, and the like.
The organic light emitting diode has been spotlighted as a next-generation display due to self-emission, a wide viewing angle, and a thin film type but in general has a drawback of a short life-span due to rapid aging by moisture and the like. In order to overcome this drawback, a method of stopping moisture and out gas from a chemical material and the like used in a manufacturing process as well as the manufacturing process itself has been adopted.
In particular, the organic light emitting diode may have a problem of a pattern collapse during thermal curing, when a fine structure such as an insulation layer, a planarization layer, and the like is formed. Accordingly, there is a need for a photosensitive resin film 1) having a cross section of a forward taper shape, 2) maintaining a pattern shape even during curing, 3) being heated and baked at 250° C. or a lower temperature, 4) generating out gas in a small amount after the heating and baking, and 5) having excellent heat and chemical resistance and the like.